The present invention relates to an image processing method and apparatus and, more particularly, to a method to search for an image in an image database, and the apparatus capable of employing the method.
As one of the conventional methods to search for a necessary image out of an image database, there is a method in which an operator makes an example of the desired image, and that the search is performed with reference to color information of the image. The color information is extracted from the desired image by using a color perception space which is composed of three elements, namely, hue, chromaticity, and luminance (altogether, called `the three attributes of colors`, hereinafter). Then, similarity between the extracted color information of the desired image and color information extracted from an image stored in the image database by employing the same color perception space, is examined. Thereby, the order of image candidates, which can be the same as, or which can be similar to the desired image made by the operator, is decided based on the similarity. The image candidate which has a higher similarity is more likely similar to the desired image. Then the images are displayed in order of similarity.
Regarding color data, each contribution factor of the three attributes of color differs in accordance with values of the three attributes of colors. For instance, in a color which has low chromaticity that is close to black or white, and low luminance, a contribution factor of hue which is an attribute to distinguish the difference of color, such as red, blue, and yellow, is also low. If the degree of similarity is calculated on the assumption that the contribution factors of the attributes are the same for all the colors in spite of the aforementioned fact that the contribution factors actually differ, the searching quality becomes lower since low contribution values are included in the calculation of similarity.